Sensor technologies

[Asbelos]

TPL handles sensors by id.

Technologies supported

1. Direct CPU pin
2. I2C expander pin

Note that the code also supports inverse sensors (e.g an IR sensor using beam-break detection where the sensor is HIGH when triggered, vs an IR obstacle-detect sensor where the output is LOW when triggered)

[davidcutting42]

I would add:

3. Layout bus pins